The major goal of the proposed research is to achieve a detailed biochemical characterization of the nerve growth factor receptor, in order to help elucidate the molecular mechanism of NGF action. The NGF receptor will be purified from human melanoma cells and the biochemical properties of the NGF receptor will be investigated. In particular, biochemical heterogeneity of the receptor which might account for observed heterogeneity in NGF binding properties will be sought, and the possibility that the receptor has a protein kinase activity, and that it may physically interact with the cytoskeleton will be explored. Monoclonal antibodies to the NGF receptor will be produced and used as an aid for receptor purification. DNA-mediated gene transfer will be used to obtain integration and stable expression of the human NGF receptor (ngfr) gene in mouse cells. After serial passage of the human ngfr gene through mouse cells by transfection, the human ngfr gene will be molecularly cloned by isolation of lambda phage recombinants containing human DNA. Nucleotide sequence data will be obtained for the cloned gene and used in conjunction with biochemical data to achieve an understanding of NGF receptor structure, and its possible relationship to the structure and function of other polypeptide hormone receptors.